The Castro government says it is willing to continue dialogue with the U.S. and is committed to cooperating to conclude the probe related to the incident with American diplomats, Minister of Foreign Affairs Bruno Rodriguez Parrilla said during a speech at the Cuban embassy in Washington D.C.

“The Cuban government is willing to continue having a respectful dialogue as well as a serious and objective cooperation with the United States and is committed to conclude the investigation to clarify these events,” Parrilla said on Thursday.

In early October, the United States expelled 15 Cuban diplomats in retaliation for what it sees as Havana’s failure to protect staff at the embassy after American diplomats came down with physical symptoms, which some US officials claimed were the result of sonic attacks.

The Cuban foreign minister also warned Washington that if they continue to politicize the issue it will set relations back even further.

Parrilla said Havana conducted a thorough investigation as soon as they heard about the incidents while cooperation from the United States has been limited.

Cuban authorities did not find a single piece of evidence to support American claims, he said.

Last month, White House Chief of Staff John Kelly said the Cuban government was capable of stopping the attacks that hurt the U.S. diplomats.

State Department spokesperson Heather Nauert said the United States knows for a fact that “somebody or something” was attempting to hurt the US diplomats and the investigation into the matter is ongoing and aggressive.

The probe, however, has not discovered what or who may have caused the sonic attacks. The United States claims at least 22 people have been affected.